* {
  margin: 0;
  padding: 0;
}
body {
  position: fixed;
  width: 100%;
  height: 100%!important;
  overflow: hidden;
  font-family: "微软雅黑";
}
body #camera {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  width: 70%;
  height: 70%;
  background: red;
}
body #camera .changeCamera {
  position: absolute;
  top: 10%;
  z-index: 100;
}
